Glucokinase
- Liver & pancreatic beta cells
- High Km & high Vmax: spares glucose for brain, muscle & other tissues (glucose sensor)
- Hormonal regulation: inhibited by glucagon, activated by insulin
- Glucokinase regulatory protein (GKRP): nuclear protein that reversibly binds/inactivates glucokinase
- High [glucose] inhibits GKRP & promotes glucokinase release
- Fructose-6P (glycolytic intermediate in equilibrium with glucose-6P): promotes GKRP-GK binding
- Liver glucose-6P shunts into one of three pathways: glycolysis, glycogen or fatty acid synthesis